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4 years ago

How many significant figures does 0.0006510 of have?

2 answers:

7 0

It has 4 significant figures. If you see the Zero after the one decimal point you don’t count that and instead just started at 6

torisob [31]4 years ago

4 0

There are 4 sig. Fig.s in 0.0006510, the 6510 are significant and the 0.000 are insignificant, as zeros can not lead and the are not captive zeros, and have no non-zero digit leading them; they are seen as insignificant zeros and not counted.

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If you combine 230.0 mL of water at 25.00 ∘ C and 140.0 mL of water at 95.00 ∘ C, what is the final temperature of the mixture?

IgorLugansk [536]

Answer: The final temperature of the mixture is 51.49°C

Explanation:

When two samples of water are mixed, the heat released by the water at high temperature will be equal to the amount of heat absorbed by water at low temperature

$Heat_{\text{absorbed}}=Heat_{\text{released}}$

The equation used to calculate heat released or absorbed follows:

$Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

$m_1\times c\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]$ ......(1)

where,

q = heat absorbed or released

$m_1$ = mass of water at high temperature = 140 g (Density of water = 1.00 g/mL)

$m_2$ = mass of water at low temperature = 230 g

$T_{final}$ = final temperature = ?°C

$T_1$ = initial temperature of water at high temperature = 95.00°C

$T_2$ = initial temperature of water at low temperature = 25.00°C

c = specific heat of water= 4.186 J/g°C

Putting values in equation 1, we get:

$140\times 4.186\times (T_{final}-95)=-[230\times 4.186\times (T_{final}-25)]$

$T_{final}=51.49^oC$

Hence, the final temperature of the mixture is 51.49°C

5 0

4 years ago

If the average speed of a helium atom at a certain temperature is 1230. m/s, what is the speed in miles per hour? (1mi =1609m)

Darya [45]

In order to do conversion on these types of problems. 
1.You first have to determine the relationship and the current unit and the target unit which it will be converted into. 
2.In this case feet to meters and seconds to minutes 
3.Determine the conversion rate: 1mi =1609 m and 1 h = 3600 sec; 
4.You first calculate: 1230 m x 1 mi/1609 m = 0.764 mi/s
5.Next, is the time which is 0.764 mi/s x 3600s/1hr = 2752.02 mi/h

6 0

3 years ago

A sample of iron contains 2.806 x 1024 atoms of iron (Fe). How many moles of iron are in the sample?

xxMikexx [17]

Answer:

Approx. 20 moles of iron.

Explanation:

There are approx. 6.022 x 10.23 iron atoms per mole of iron. In this quantity, The number of iron atoms has a mass of

55.85 ⋅ g.

4 0

2 years ago

The natural distribution of the isotopes of a hypothetical element is 60.795% at a mass of 281.99481 u, 22.122% at a mass of 283

fenix001 [56]

Answer: The average atomic mass of the element is 283.291 amu

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

For isotope 1:

Mass of isotope 1 = 281.99481 amu

Percentage abundance of isotope 1 = 60.795 %

Fractional abundance of isotope 1 = 0.60795

For isotope 2:

Mass of isotope 2 = 283.99570 amu

Percentage abundance of isotope 2 = 22.122 %

Fractional abundance of isotope 2 = 0.22122

For isotope 3:

Mass of isotope 3 = 286.99423 amu

Percentage abundance of isotope 3 = [100 - (60.795 + 22.122)] = 17.083 %

Fractional abundance of isotope 1 = 0.17083

Putting values in equation 1, we get:

$\text{Average atomic mass of element}=[(281.99481\times 0.60795)+(283.99570\times 0.22122)+(286.99423\times 0.17083)]\\\\\text{Average atomic mass of element}=283.291amu$

Hence, the average atomic mass of the element is 283.291 amu

5 0

4 years ago

What temperature, in C, would be required for 1.70 grams of oxygen gas

olga_2 [115]

Answer:

2408.1 °C

Explanation:

Given data:

Mass of oxygen = 1.70 g

Volume occupy = 9.75 L

Pressure of gas = 799 torr (799/760 = 1.1 atm)

Temperature = ?

Solution:

Formula:

PV = nRT

First of all we will determine the number of moles of oxygen.

Number of moles = mass/ molar mass

Number of moles = 1.70 g/ 32 g/mol

Number of moles = 0.05 mol

Now we will put the values.

R = general gas constant = 0.0821 atm.L/ mol.K

T = PV/nR

T = 1.1 atm× 9.75 L /0.05 mol ×0.0821 atm.L/ mol.K

T = 10.725 /0.004

T = 2681.25 K

kelvin to °C

2681.25 K - 273.15 = 2408.1 °C

8 0

3 years ago